This invention relates to improvements in the field of high field resistance magnet coils, and more particularly but not by way of limitation, to superconducting coils that are provided with metallic insulation, preferably coated with its own oxide, to increase resistivity and to provide, for example, turn to turn insulation.
Superconducting coils used in future Tokamak or mirror configured fusion power reactors will be subjected to high influences of neutron radiation. Due to the intense neutron environment in such high field magnet coils, (18-24 Tesla) organic composite insulators such as glass fabric epoxy/polyimide composites, will degrade in mechanical strength and electrical insulation properties over a short period of time. Ceramic insulators like aluminum oxide (Al.sub.2 O.sub.3) or spinel (MgAl.sub.2 O.sub.4) are more radiation resistant than glass fabric epoxy/polyimide insulators and may perform acceptably for extended periods. But these ceramic insulators have a serious fabrication problem in that they are brittle and have very little ductility.
These shortcomings severely limit new reactor designs by requiring large amounts of shielding to reduce the neutron flux to an acceptable level. Typically, the most conventional method of insulating coils of a superconducting magnet is with epoxy/glass fabric laminates (G-10CR) and Kapton film. Such organic materials would have extremely short lives in the expected neutron flux of 10.sup.21 RADS per year. Resistive insert coils for typical mirror fusion machines have an inside diameter of 8 to 9 inches. This does not leave room for shielding from the plasma. Obviously, a need exists for an insulation that will extend the insulation life to that of the basic coil.
Further, it would be desirable to be able to use an insulation that has a higher modulus and has higher allowable bearing stress than the organic insulations. This will result in less conductor pack deflection and conductor movement. It is desirable to keep conductor movement to a minimum, since it can cause the conductor to go normal, that is to a non superconducting state.
It is believed that the shortcomings of the previous available insulations have been overcome by the provision of the insulation of the present invention.
The invention will become better understood by reference to the following detailed description when considered together with the accompanying drawings, in which: